SDL_ttf: DPI-scalable rendering? (patch is available!)

Hello!

With the recent set of SDL releases out the door, any chance I could get a review of a patch that enables DPI-scaling to SDL_ttf? If so, info on it is posted at https://bugzilla.libsdl.org/show_bug.cgi?id=2951

This change has been used to help support things like iOS-aware Retina scaling (to 2x, 3x, etc.), in some released apps.

Cheers!
– David L.